Cracked biofalls box

A customer has a cracked Endless Cascades falls box. It's outside of the 1 year warranty, i'm rather surprised a plastic box that cost a couple hundred dollars only carries a 1 year warranty but anyways. He is looking at repairing the crack versus replacing. He found a pond repair product by Sani-Tred products but it looks to be for concrete ponds. My first thought is to use marine epoxy putty, we use this on boats when we are fishing the rocky rivers around here. The distributor said he used several layers of silicone on his. His also cracked and said the are known to crack. Any thoughts??

In my 15+ years of working in this industry, I have never seen a biofalls or skimmer box crack or split, but I have only dealt with the better known brands which are constructed of heavy ABS. I have seen them bowed and severely buckled but still maintained their structural integrity.
A one (1) year warranty should have been a warning sign. I know of no product available for field use that will patch/repair a crack to a level that will resist the pressures that these units experience from the surrounding soil.
Rip it out and install a unit that is manufactured by one of the better known manufacturers. Remember, when you buy cheap, you get cheap!